Synthesis and algicidal activity of new dichlorobenzylamine derivatives against harmful red tides

Abstract

In the present study, we synthesized 65 dichlorobenzylamine derivatives and investigated their algicidal activity against harmful red tides. The 3,4-dichlorobenzylamine derivatives showed relatively high activity against Cochlodinium polykrikoides, Heterosigma akashiwo, Chattonella marina, and Heterocapsa circularisquama, and the synthesized compounds 27, 28, 33, 34, 35, and 36 showed the highest algicidal activity after 24 h at 0.1 similar to 1.0 mu M LC50 against the four harmful algae species. To verify the safety of the compounds, acute ecotoxicology tests using the water flea (Daphnia magna) and zebrafish (Danio rerio) were conducted, and the tests confirmed that compounds 33 and 34 were not harmful because the target organisms showed high survival rates at 15 mu M. The results indicate that compounds 33 and 34 are suitable substances for use in controlling harmful algae species.